In good company! Kate Middleton laughs and jokes with Wimbledon chief Philip Brook in royal box

Duchess of Cambridge watched Serena Williams take on Russia's Elena Vesnina in a Roksanda dress.

Catherine, Duchess of Cambridge, Philip Brook and Sophie, The Countess of Wessex look over the outdoor courtsJordan Mansfield/Getty Images

The Duchess of Cambridge may have graced Wimbledon on Thursday (7 May) without the company of her husband, Prince William, but another man made her grin from ear to ear as Serena Williams took on Elena Vesnina during the Ladies Singles semi-final game all the same – Wimbledon's chairman Philip Brook.

Looking resplendent in a colour block yellow and white £900 dress by Roksanda – which she had previously worn during a Royal tour of Australia in 2014 – Kate Middleton was in high spirits as she mingled with fellow Wimbledon-goers without the Duke of Cambridge and her two children, Prince George and Princess Charlotte.

But there wasn't a shortage of people to invoke her trademark gleaming smile – she was spotted laughing and joking with Sophie, the Countess of Wessex, and more frequently, Wimbledon's chairman Brook. Sophie, the wife of Prince Edward, oozed elegance in a summer outfit comprising of a pink voluminous skirt and white boxy top featuring diaphanous sleeves.

Regular attendee of the royal box, Brook, enjoyed chatting to the Duchess immensely as the pair sat next to each other and beheld 21-time grand slam champion Williams beat Russia's Vesnina after 48 minutes (6-2 6-0). The pals were also spotted on the balcony over the outdoor courts during the Wheelchair Singles matches.

Philip Brook and Catherine, Duchess of Cambridge watch on from The Royal Box on day ten of the Wimbledon Lawn Tennis ChampionshipsAdam Pretty/Getty Images

Kate divulged to Britian's former number one Greg Rusedski that the toddler has shown a great interest in the sport. Speaking of their conversation, he said: "She talked about George, her little boy, playing tennis. He's got a racket and he enjoys playing tennis, and obviously she plays with William. So they obviously enjoy the sport very much."

Catherine, Duchess of Cambridge and Phil Brook watch on from The Royal Box as Serena Williams cruises into the finalBen Curtis/AP/Pool/Getty Images

Praising the Duchess, Rusedski added: "She was very friendly. I think everyone was delighted to meet her today at Wimbledon and she's obviously a great ambassador for the country," he said.

Catherine, Duchess of Cambridge and Phil Brook watch on over the outdoor courts during the Wheelchair Singles matchesJordan Mansfield/Getty Images